I have been trying, over my last 10 weeks or so of pregnancy, to write down any potential blog post topics based on things I’ve thought about; worried about; had to do; or that are relevant to different stages of pregnancy.
One topic that I think fills the minds of moms-to-be, especially first timers, is all the testing. Understandably so – I think it can be equally as thought consuming in each pregnancy really. So I thought I’d break down the options that may be available to you if you live in Ontario. I apologize as I am not as familiar with other provinces/countries options and they do vary a bit.
I will try and provide some links at the end for other areas – and as always, your health care provider remains your best source of information! I strongly recommend talking options out in detail with your provider and asking any questions you may have, or following up if any questions come up after the fact.
Disclaimer: this blog is for informational purposes only. This is not medical advice. Please seek medical advice from your healthcare provider.
Enhanced First Trimester Screening (eFTS)
eFTS is a combination test that is looking at risk for two chromosomal differences – Trisomy 18 and Trisomy 21 respectively. You may know these as Edwards and Down syndrome, respectively. Click the names to learn more.
When I say combination testing, I mean that you get bloodwork and an ultrasound done for this testing. The ultrasound is done first followed by the blood work – it is the easiest if you can do them in the same day (I found personally) however you have until 13+3 (or 13+6 – please ask your own provider for instructions/time span) approximately to complete the bloodwork.
The blood test looks at 3 proteins and a hormone (hcg) in your blood. You can read more about them and what they mean here.
The ultrasound scan is also called a nuchal translucency scan – it is looking at a fluid pocket at the back of your baby’s neck. The ultrasound technician takes photos and measurements of this area, and other measurements such as the crown-rump length (CRL) for example, which are then reviewed by a radiologist before a report is sent to your provider. The nuchal translucency being larger than >3.5 mm measured can be a flag for the chromosomal differences mentioned above.
The eFTS is probably the most common prenatal testing I saw done in primary care. It is low risk compared to some other forms of testing that can be done in pregnancy. Most parents do seem to opt to pursue this, but the testing should be discussed in depth with your provider. Don’t be afraid to ask questions as needed.
If you are already thinking of pursuing something like the NIPT (which I will discuss below) then this testing does not usually need to be done, however the NT ultrasound can still be beneficial.
When should I get this done?
Your provider will advise you of the window of time in which the testing should be done based on your dates – it is recommended between 11+2 and 13+3 weeks gestation in Ontario. This recommendation may very slightly between a few days depending on where you are reading or where you live. The general recommendation is between 11 weeks and the very end of the 13th week (13+6). Review with your provider about the best time to go – if you didn’t have a dating scan done (not everyone does), then your provider may recommended waiting until the middle to late period of that span to go for example.
You should receive a prenatal screening requisition from your provider at your first prenatal appointment which you take with you to the ultrasound as well as to the lab. You will probably get a separate ultrasound requisition and blood work requisition too – it’s common for your other routine prenatal bloodwork to be done at this same visit.
When should I be concerned?
I would advise you not to read too much into your own results until you can speak to your provider, and until the eFTS results (of the ultrasound + bloodwork) arrive for their review. I know it is easier said than done when you’re already anxious.
An NT measurement of >3.5 mm is considered increased and will require follow up testing. This will be discussed with you by your provider.
How accurate is the test?
There are possible areas of error for this test. It is not perfect.
Things like human error or baby’s position (or even the cord being around their neck) can render incorrect measurements (false positives). On the other side of that, measurements can also be smaller for similar reasons (false negatives). This is why I recommend waiting till your follow up call or visit with your provider, so that the whole picture can be provided and next steps can be discussed for further testing if needed.
The screening test does have relatively good sensitivity, which is why it is used and recommended. The false positive rate for this test is higher in regards to Trisomy 21 risk (7%) than Trisomy 18 (0.2%). Similarly the detection rate (when the test prediction is correct) is also improved with Trisomy 21 (89%) when compared to Trisomy 18 (78%).
Are there other testing options?
Yes – the Non-Invasive Prenatal Testing (NIPT) is a popular option and is more than 99% accurate at detecting Trisomy 21 differences and 95% accurate for Trisomy 18 differences. It also screens for Trisomy 13 (Patau syndrome) and by request, any differences in the sex chromosomes. As a result, you can also find out baby’s sex early through the NIPT.
At some labs, other smaller chromosomal differences that occur through deletions of parts of chromosomes can also be screened for, however the accuracy of these screenings is not as good as the above differences because many of the syndromes it is looking at are rare in the general population. That means there is less existing data on them in general. There are many local and international initiatives to increase and improve the data that is available for many of these less common chromosomal abnormalities. So hopefully in the future we can improve these tests with increased data and knowledge.
When do I need to have this testing done if I want to pursue it?
If you choose to get the NIPT, as I mentioned above you don’t need to get the eFTS as well, though your provider may still recommend the ultrasound (NT) scan.
This testing can be done earlier than the eFTS starting at 9 weeks (at some labs it may be 10 weeks, so check ahead). It can also be done at various times throughout pregnancy, which gives you a much larger window of time than the eFTS. It can also be done following a positive eFTS for example.
Is the NIPT covered by OHIP?
It may be but you have to meet certain criteria.
- NT measurement >3.5 mm
- 40+ year old maternal age at EDD (or at egg retrieval time for IVF)
- Personal history of any of the chromosomal differences listed above in a past pregnancy or child
- Positive multiple marker screening (MMS) – so either the eFTS is positive or another test called the Maternal Serum Screening (MSS) is – this blood test is offered in the second trimester (14-20+6 weeks gestation) also looking at Trisomy 18 & 21 (keep in mind, it also looks at risk/chance of), it is mainly for those who missed that short eFTS window or who could not have an NT scan
During the pandemic there have been some additional criteria added, and there are a few others that can be found here.
You can still choose to pursue the NIPT if you don’t meet any of the criteria of course, but it would be paid for privately. Some insurance companies through an employer may provide coverage for this as well. Ask your provider about where to have this done – our local labs do offer private-pay NIPT options. You can also find out pricing by looking on their websites or inquiring by telephone.
The follow up testing I have referred to usually involves (after the NIPT) more invasive testing that can provide diagnostic information. I will share a follow up post on these options!
Hopefully this is a helpful overview. I find that Prenatal Screening Ontario is an excellent resource and you’ll notice I pulled a lot of the statistics from there and linked back to them often. The best resource though? Always you provider. They are the ones following you through pregnancy, who know your medical history and current state, and can provide you with evidence-based answers to your questions.
My Personal Experience with Prenatal Screening
I have personally done the eFTS testing in both pregnancies so far and it has been very easy.
My suggestions would be:
- Find a diagnostic (x-ray/ultrasound) lab that has good reviews from those you know or even Google reviews – I find it is very comforting during the NT scan to have a technician with good bedside manner. Unfortunately, my first NT scan I left feeling very worried and it was for no reason at all – simply a lack of engagement/kindness from the technician. My second scan was amazing and I will do all my scans at the same location now. Techs can’t share any info, but they can speak to you nicely and be empathetic especially to mom’s experiencing anxiety.
- Do your bloodwork on the same day – it’s easier to get it all over and done with. The only time I’d suggest waiting is if you maybe have increased anxiety or you’re not good with having blood taken. If it’s the latter option, I suggest finding a lab or location to go to that may be more supportive of this. Unfortunately with the pandemic having a support person many places is not an option – but again good reviews can point you in the right direction or your provider may have specific suggestions as to where to go (same with for the ultrasound).
- Don’t panic – trust me, I know – easier said than done. I remember being extremely nervous the first time because we were leaving for Ireland the day of our testing. Ask your provider in advance how they deal with results (some places work on a “no news is good news” method, and they will just discuss the results with you at your next visit for example).
- Don’t be afraid to ask questions before/while you wait/after – and ask about your options for testing!
I’d also highlight and emphasize the don’t panic point. Speak to your provider if you have worries or concerns. And remember it’s your baby & body – speak up for both and advocate for yourself where you can. What you want and need matters.
Resources for Non-Ontario Residents
If you’re in the USA please check out the ACOG’s page on prenatal screening tests. You can also refer to your state/areas health departments (same as for other locations in Canada). Please speak to your provider as I recommended above – your best resource!